Redundant flight control systems that include two or more vehicle management computers (VMCs) are used on UAVs to increase the reliability of the UAVs. Such redundant control systems are operated in parallel and can share data relating to the control of the UAVs. The control systems must be synchronized to achieve a smooth transfer of control from one VMC to the other, to simplify the control processing logic and to ensure that each VMC can share state information without large time skews. One unmanned aerial vehicle (UAV) uses a dual-redundant flight control computer (VMC) architecture running in a frame-synchronize manner to achieve the goal of less than one catastrophic lost of an air vehicle in two hundred flights.
To achieve a lower probability of catastrophic loss, a multi-redundant UAV VMC architecture could be used. Thus there is a need to provide synchronization of the frame clocks of a multi-redundant UAV VMC architecture.